The alteration of the colour of hair by the application of hair dyes is well known.
In order to provide the consumer with the hair colour and intensity of shade desired, a very complex chemical process is utilised. The hair dyeing molecules are typically produced from the reaction of at least one oxidative colouring agent with an oxidising agent which are formed in situ on the hair of consumers and typically in an aggressive environment at ca pH 10 and in the presence of alkalising agent. Moreover this process is repeated regularly by the consumer in order maintain the desired hair colour and intensity of the hair colour shade and ensure continual, even coverage of the hair including coverage of new hair growth.
The manufacturer of such products is also required to work within a large number of constraints. Since these products are being placed in direct contact with the consumers' skin and potentially accidental contact with the eye or ingestion (for example) can occur during the dyeing process, the formulation must meet rigorous safety requirements and not cause any allergic reaction. In addition to meeting these requirements, the products must also be optically and olfactory pleasing to the consumer and meet certain physical parameters in order to ensure that the product can be easily applied to the hair by the consumer to provide the desired effect, without unintentional staining on the consumers clothes, skin or other objects.
The chemistry involved in the hair dyeing process may result in some damage to the hair which is permanent. Damaging effects include tangling, brittleness and dryness. Consequently there is a need to provide the hair dye composition or hair dyeing kit with a conditioning component in order to combat this damage and improve at least the consumers' perception of the condition of the hair; immediately after the hair dyeing process and the on-going condition of the hair during the post dyeing washing cycle until the next hair dyeing cycle.
The use of conditioning compositions is well known in the art and are incorporated as part of conventional shampoo and conditioning regimes as well as in so called two-in-one shampoo conditioners. Their use in hair dyeing kits is also well known. Typically they are provided in a sachet for use in the final rinse, after dyeing is completed. These conditioners such as amino silicones as described for example in U.S. Pat. No. 4,563,347, EP 275 707 and WO99/49836 usually provide an acceptable immediate improved feel of the hair to the consumer. However, this conditioning benefit is not durable over a number of hair washing cycles such that the consumer becomes dissatisfied with the condition of the hair during the course of the post dyeing cycle.
Unfortunately durable conditioning cannot be achieved by simply increasing the levels of conditioning material in the composition. In fact, if excessive conditioner is applied, the initial feel of the hair becomes heavy and greasy which is completely unacceptable to the consumer.
Moreover if the conditioning material is such that it is sustained on the hair during the post dyeing wash cycle such that it is still present on the hair at the start of the next colouring cycle, the performance of the dyeing process cannot be predicted and may be detrimentally effected. Such a result is equally undesirable for the consumer.
Progress has however been made in the field of durable hair conditioning materials and in particular compounds such as amodimethicone have been identified as delivering improved durable conditioning benefits.
It has further been taught in the art for example in WO99/49836 to utilise microemulsions of organosiloxanes in order to improve the conditioning effect.
However, there is still a need to provide durable conditioning materials for use in hair dye compositions which have the required initial deposition and retention over time without any greasy feel negatives after the initial application and which do not negatively affect the performance of the next hair dyeing cycle.
There is also a need to provide a hair dye composition which does not necessarily require a separate post hair dyeing conditioning step.